docs: def com_google_fonts_check_family_equal_unicode_encodings(ttFonts):
    """Fonts have equal unicode encodings?"""
    encoding = None
    failed = False
    for ttFont in ttFonts:
      cmap = None
      for table in ttFont['cmap'].tables:
        if table.format == 4:
          cmap = table
          break
      # Could a font lack a format 4 cmap table ?
      # If we ever find one of those, it would crash the check here.
      # Then we'd have to yield a FAIL regarding the missing table entry.
      if not encoding:
        encoding = cmap.platEncID
      if encoding != cmap.platEncID:
        failed = True
    if failed:
      yield FAIL, "Fonts have different unicode encodings."
    else:
      yield PASS, "Fonts have equal unicode encodings."